Support numpy arrays in model_config

[michaelraczycki]

This PR addresses issue mentioned in #348. As on the development stage only certain priors were shown to use arrays, I didn't include it at the time, but seeing users trying to include them I've added more thorough algorithm to scan all the fields of model config and ensure their JSON serialization.

Closes #333
Closes #348

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📚 Documentation preview 📚: https://pymc-marketing--351.org.readthedocs.build/en/351/

[codecov]

Codecov Report

Merging #351 (8a6b81b) into main (8c38233) will decrease coverage by 2.23%.
Report is 3 commits behind head on main.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #351      +/-   ##
==========================================
- Coverage   95.85%   93.62%   -2.23%     
==========================================
  Files          19       20       +1     
  Lines        1447     1664     +217     
==========================================
+ Hits         1387     1558     +171     
- Misses         60      106      +46     

Files Changed	Coverage Δ
pymc_marketing/mmm/delayed_saturated_mmm.py	100.00% <100.00%> (+0.53%)	⬆️

... and 6 files with indirect coverage changes